Shutterings and Mutterings - photography blog

Motoring with rear curtain flash

If you’re not familiar with flash photography, I’ll explain quickly. Flash can be synchronised to fire as the shutter opens and therefore at the start of the exposure – this is called first or front curtain flash. Alternatively, the flash can be set to fire just before the shutter closes at the end of the exposure – known as second or rear curtain flash. If you’re working with a fast shutter speed, one capable of freezing movement, it will not make a huge difference which one you use. However, when you are working with slow shutter speeds and moving subjects, there is a lot of creative fun to be had with second/rear curtain flash.

In the example above, the shutter was open for about one third of a second as the toy car was passing in front of the lens. It was lit throughout the exposure by two battery-operated torches – these create the cartoon-like ghosting and light trails – and the flash froze it at the end of the exposure. If the flash had fired at the start, the ghosting and light trails would appear to be running ahead of the car and that would simply look odd.

For this set-up, I used a large piece of black card as the backdrop and a large, flat black cardboard box as the track. The camera – a Nikon D40 – was set up on a tripod and fired by a remote trigger on two-second delay. For lighting, I used two battery-operated torches and the camera’s built-in flash. As the car’s movement can be rather erratic, I set the aperture to f18, ensuring a deep depth of field and improving the chances of getting a reasonable focus.

I placed the car in its ideal running position and set the focus manually. I took a static test shot to determine the flash level and confirm the focus - I knew I wanted to use an exposure time of about 0.3 or 0.5 of a second so I adjusted the flash strength until I got the result above – strong light on the subject without much shadow falling onto the background. It was time to wind up the motor and set the wheels in motion...

The process involves a fair bit of trial and error and requires time and patience. However, when you capture those cartoon-style light trails, the effort is well rewarded.